1. Field
The disclosure relates to a method, system, and article of manufacture for the decryption of data in storage systems
2. Background
Encryption of data in a network may be categorized into two different types—encryption of “data in motion” and encryption of “data at rest”. Encryption of “data in motion” provides security to data as the data is moving across the network between a sender and a recipient. “Data in motion” may also be referred to as “data in flight”. Encryption of “data at rest” is the encryption of data that is being stored in a storage medium and is not undergoing transmission. For example, the encryption of data stored in a disk or the encryption of data in a database may be referred to as encryption of “data at rest”.
Encryption of “data at rest” is desirable for protecting data stored in a disk. Encryption of data performed via hardware is referred to as hardware encryption, and encryption of data performed via software is referred to as software encryption. While hardware encryption is faster in comparison to software encryption, such hardware encryption may not be available in many situations, e.g., hardware encryption may not be available on certain disk Fibre Channel interfaces. In many cases, software encryption is used for the encryption of “data at rest”.
Certain disk staging algorithms perform speculative prefetching of data from secondary storage to the cache to improve the read hit ratio on the cache. Performing decryption on the speculatively prefetched data can lead to performance degradation. Reducing the amount of data that is speculatively prefetched can reduce the amount of decryption to be performed. However, reducing the amount of data that is speculatively prefetched may lower the read hit ratio and degrade performance. Speculative prefetching is often used in storage systems because once the disk head is positioned on the desired data, transferring additional data to cache along with the desired data takes very little additional time in comparison to the time taken to position the head on the desired data.